1. Field of Technology
This application relates generally to spinal fusion. More specifically, this application is directed to a pre-packed corpectomy device and method of bridging vertebrae with the corpectomy device to improve fusion.
2. Brief Description of Related Art
Spinal surgery frequently requires reconstruction of the anterior spinal column. Spinal vertebrae are bony cylindrical structures that are located in front of the spinal cord and nerves; they contribute to the structural support of the axial skeleton. A vertebra can be damaged or destroyed by disease or trauma, resulting in the compression of the spinal cord and/or loss of structural integrity of the spinal column. When the vertebra is removed during spinal surgery to decompress the spinal cord and/or restore structural integrity of the spinal column, it is necessary to reinforce and stabilize the anterior spinal column. A bone graft (e.g., from patient's hip) has traditionally been inserted into a defect site to bridge or fuse the vertebrae above and below the removed vertebra.
While there have been significant efforts to develop artificial weight-bearing devices, the materials that are suitable for the manufacture of these devices do not allow for bone integration. Accordingly, the devices need to have sufficient amount of interior space to pack grafting material, which can facilitate bone integration between the vertebrae. During spinal surgery, a surgical corridor is formed to the defect site, e.g., the diseased or damaged vertebra of the anterior spinal column. The corridor is generally as narrow as possible because there are sensitive and vital structures in front of the anterior spinal column that can be damaged.
To accommodate the materials and the surgical corridor, weight-bearing devices have been designed to have telescoping components that provide vertical expansion from a collapsed state during insertion to an expanded state after insertion into the defect site. Various expansion mechanisms have been designed to facilitate expansion and locking of the telescoping components with respect to one another. Generally, weight-bearing devices that have expansion mechanisms, which are easiest to actuate in the defect site, have the bulkiest exterior dimensions and/or take up the most interior space in the weight-bearing devices, negatively affecting fusion as they do not have sufficient amount of interior space to pack grafting material.
Accordingly, the following characteristics are desirable in an artificial weight-bearing device. It should have proper structural (or weight-bearing) properties. It should have a modulus of elasticity that is close to bone. It should be low profile to facilitate insertion. It should have the ability to expand after insertion into the defect site to accommodate defect sites of various patients. The expansion mechanism should be low profile and easy to actuate. The weight-bearing device should have a sufficient interior space to accommodate grafting material in order to achieve bone integration. It should further facilitate pre-packing of the grafting material before insertion into the defect site. Further, the pre-packed grafting material should be packed tightly after expansion of the device in the defect site.
Currently available artificial weight-bearing devices do not meet the foregoing criteria and require significant improvement. One of the most critical shortcomings is that there is little interior space for pre-packing of grafting material while the device is in a collapsed state. Further, when the device is expanded in the defect site into its expanded state, the grafting material loses its packing inside the interior space of the device. Post-packing the interior space of the device—while the device is expanded in the defect site—is not desirable and presents a danger of dislodging the device or impacting the device into the vertebrae.